1. Field of the Invention
The invention relates to the field of wheels, each of which includes a rim, a hub, and at least one device for connecting the rim to the hub, with the connecting device including at least one composite spoke and one mechanism for connecting the spoke to the rim or to the hub. The invention also relates to the connecting device itself.
More particularly, the invention relates to wheels and connecting devices of the aforementioned type, which are adapted to bicycles, as well as to other vehicles such as wheelchairs, or the like.
2. Description of Background and Relevant Information
A device for connecting the rim of a spoked wheel to a hub includes, by definition, at least one spoke. The spoke has an elongated body that extends between a first end and a second end.
Conventionally, a spoke is made of metal, because metal facilitates the shaping of the ends. An end can be configured, for example, to enable the end to be fastened directly to the rim or hub, such as by means of a threaded end, or to be threaded for cooperation with a correspondingly threaded nut. An advantage of a metallic spoke, therefore, is that the fabrication of the spoke is easy and inexpensive.
However, metallic spokes have drawbacks, such as their heavy weight, which adds to the weight of the wheel and, of course, the overall weight of the vehicle to which the wheel is a part. Another drawback of metallic spokes is their relatively low resistance to tension forces or material fatigue, which requires that the tension in each spoke be monitored during assembly and use.
In order to remedy these drawbacks, the prior art has proposed to make a spoke that includes a composite material, such as, for example, resin-bound carbon fibers.
In this regard, the patent document FR 2 762 267 discloses the manufacture of a spoke having a body made of composite material, which includes two straight elongated portions united by two rounded portions. The spoke thereby has the general shape of an oblong ring. An advantage of this structure is a reduced weight, which lightens the weight of the wheel. Another advantage is a great resistance to tension or fatigue. Thereby, the wheel requires less maintenance.
The use of the spokes according to the document FR 2 762 267 has drawbacks, however. For example, the arrangement by which the spoke is connected to the rim or to the hub is heavy and complicated. Indeed, such arrangement includes a shank, which extends the rounded portion of the spoke, as well as a clevis, which is connected to the shank. The combination of the shank and the clevis forms a bulky and heavy articulation. Furthermore, its implementation is complicated because some provision is required to be made for connecting the clevis to the rim or to the hub. As a consequence, the benefits gained in a reduction in the weight of the body of the spoke are lost, at least in part, by the disadvantage in the increase in the weight of the connection.
Modifying the structure of a composite spoke, therefore, has been proposed.
For example, the patent document FR 2 792 251 proposes a spoke made of a composite material. The body of the spoke includes a single elongated portion that extends between a first end and a second end. Each end is formed as a loop inside of which a reinforcing core is housed. To connect an end to a rim or hub, a hollow cap is provided to receive the loop, as well as a hollow screw that receives the cap.
The advantage of the spoke according to the document FR 2 792 251 is that it is lighter due to the structure of its body. However, the connection assembly with which it is associated remains relatively bulky and heavy because they enclose the loops. Furthermore, manufacturing and implementing the connection assembly are relatively complicated.
As with the spoke and connection assemblies of FR 2 762 267, the benefits gained in the reduction in weight of the body of the spoke of FR 2 792 251, which are made of a composite material, are lost, at least in part, by the disadvantage in the assembly for connecting the spoke to the rim and/or for connecting the spoke to the hub. Furthermore, the connection assembly for FR 2 792 251 is relatively complex.